Photographic developers containing polyalkylene glycols



United States Patent 3,158,483 PHOTOGRAPI-HC DEVELDPERS CQNTAENlN'G RGLYALKYLENE GLYCQLS Wesley G. Lowe and Judith A. Schwan, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y-, a corporation of N ew Jersey No Drawing. Substituted for abandoned application Ser. No. 644,746, Mar. 8, 1957. This application Feb. 9, 1962, Ser. No. 172,097

5 Claims. (Cl. 9666) This invention relates to photography and particularly to improved photographic developers.

This application is a substitute for U.S. application Serial No. 644,746, filed March 8, 1957, now abandoned.

Photographic films used in the graphic arts for making half-tone or line images should be capable of producing extremely high contrast and good image sharpness. These factors contribute in the case of half-tone images to high dot quality, that is, to the production of halftone dots of high density and sharpness. In many cases, the photographic developers intended to produce high contrast images do not produce the high contrast desired, or if they produce high contrast images are deficient in tray life, that is, resistance to aerial oxidation.

It is therefore an object of the present invention to provide a method and developer for producing high contrast photographic images. A further object is to provide a photographic developer capable of giving high contrast and at the same time having good aeration life. A still further object is a photographic developer capable of producing half-tone images of good dot quality. Other objects will be apparent from the following description of our invention.

These objects are accomplished by developing an exposed photographic silver halide emulsion, especially an emulsion designed for producing a high contrast image, in a solution of a p-dihydroxybenzene developing agent containing a polyalkyleneglycol, less than about 5 grams per liter of any dissociated sulfite and substantially no aminobenzene developing agent. However, relatively large quantities of an un-ionized sulfite, such as sodium formaldehyde bisulfite, may be present.

Our invention comprises in its broader aspects the use of a hydroquinone or substituted hydroquinone developing agent in a developing solution containing a polyalkylene glycol, especially a polyethylene glycol or one of its derivatives as hereinafter described, the solution being of low sulfite content, that is, containing less than 5 grams per liter of any sulfite. The solution should also be free of aminobenzenedeveloping agent such as the N-methyl-p-aminophenol commonly used.

Photographic emulsions designed for producing high contrast images such as Kodalith films (see Kodak Graphic Arts Films and Plates, Eastman Kodak Company, 1951) produce images having a gamma of 9 to 10 and half-tone dots of good qualitywhen developed in a suitable developing solution. However, it is desirable to increase the gamma obtainable in such emulsions and to improve half-tone dot quality, and the present invention enables this to be done.

Our developing solutions contain a p-dihydroxybenzene developing agent such as hydroquinone, toluhydroquinone, 2,5 dimethylhydroquinone, 2,5 diethylhydroquinone, etc., but are substantially free of aminobenzene developing agent such as p-aminophenol, N-methyl-paminophenol, p-phenylenediamine, etc. By substantially free we mean that the developing solution contains less than 0.05 gram per liter of these developing agents.

Our developers should contain little or no sulfite preservative, that is, sodium sulfite, sodium bisulfite, potassium metabisulfite, tc. While this sulfite compound need not be entirely excluded from the developer its contents should not be greater than about 5 grams per liter of solution.

The polyalkyleneglycol or alkylene oxide polymers used in the developing solution are polymers derived from alkylene oxides containing from 2 to 4 carbon atoms, e.g., ethylene oxide, propylene oxide and butylene oxide. The preparation of polymers from these compounds is described in Ellis, The Chemistry of Synthetic Resins (1935), page 990 to 994. Various derivatives of alkylene oxides may also be used in the developing solution, e.g., condensation products of alkylene oxide with glycols such as those having from 8 to 18 carbon atoms as described in U.S. Patent No. 2,240,472 and British'Patent 443,559, as Well as condensation products of alkylene oxides with aliphatic alcohols, aliphatic acids, aliphatic amines and phenols, that is, polyalkylene ethers, esters and amides, the preparation of which is described in U.S. Patent No. 1,970,578, and condensation products of alkylene oxide with hexitol ring dehydration products as described in U.S. Patent No. 2,400,532. These compounds should have a molecular weight of at least 400 and preferably from 1500 to 4000. The lower members of this group (molecular weight 400 to 1000) are difficult to handle due to their viscosity and tend to leave oily residues during processing. Polymers having a molecular weight of about 1000 and above are solids and are more easily handled. These compounds are sold by Carbide and Carbon Chemicals Corporation under the trade name Carbowax, e.g., Carbowax 1500, Carbowax 4000, Carbowax 6000, the numerals usually indicating average molecular weight. Carbowax 1500, however, has an average molecular weight between 500 and 600.

The following are examples of alkylene oxide polymers which we may employ:

Polyethyleneglycol 400 Polyethyleneglycol 600 Polypropyleneglycol 425 Polyglycol E-IOOO Polyglycol E-4000 Polyglycol E9000 (These compounds are sold by Carbide and Carbon Chemicals Corporation and are believed in the case of the ethylene oxide polymers to have the general formula HOCH CH O (CH O CHgCHgOH Our invention will. now be more specifically illustrated (made by condensing 1 approximately 15 moles of by reference to the following examples:

Example 1 Grams Hydroquinone 10 Sodium sulfite (desiccated) 2.5

Potassium bromide 2.4

Sodium carbonate, monohydrate 17.5 Water to 1 liter.

This developer had a pH of 10.1.

Strip 10/i Speed Gamma Fog Example 2 An emulsion similar to that used in Example 1 was exposed in the same way, a half-tone screen being inan alkylene oxide polymer selected from the class consisting of (1-) condensation productsof alkylene oxide with glycols, and (2) condensation products of an alkylene oxide with aliphatic compounds se- 5 lected from the class consisting of aliphatic monohydric alcohols, aliphatic monobasic acids, aliphatic monoamines and monohydric phenols,

said alkylene oxide containing from 2 to 4 carbon atoms and said alkylene oxide polymer having a molecular weight of at least 400, and said developer containing susbtantially only said p-dihydroxybenzene developing agent as developing agent for silver halide.

2. A photographic developer capable of producing high contrast images upon photographic development comprising a. developing solution containing a p-dihydroxybenzene developing agent,

an amount of dissociated sulfite less than about 5 serted in the exposing beam. Several strips were exposed grams P liter, p in this way, and after developing them in the followin a polyethylene glycol having a molecular weight of developer to which the amounts of polyethyleneglycol least and indicated in the table were added, fixing and washing, the Sand developer comammg Wbstamlauy only said P results shown in the table were obtained. y r y nz ne devcloplng agent as developing agent for silver halide. Developer: Grams 3. The developer of claim 2 inwhich the p-dihydroxyfiyqroqumone 10 benzene developing agent is hydroquinone. Sodlun} sulfite (fieslccated) 4. The developer of claim 2 in which the p-dihydroxy- W K bromlde benzene developing agent is hydroquinone, the polyethylsodlum blcarbonate eneglycol is the oleyl ether of polyethyleneglycol and the Sodlum carbmate monohydrate 22 dissociated sulfite is sodium sulfite in an amount of about Water to 1 hter- 2.5 grams per liter, the developer being free of other sulfite. De pe 5. The method of developing a high contrast photo.- t 3 fi$$ gfifi ii Gamma E EE graphic image in an exposed silver halide emulsion layer v r which comprises developing said exposed emulsion layer 1 in a photographic developer containing. Control g 33 Pg a p-dihydroxybenzene developing agent,

hi 1 1 6 1 3 an amount (if dissociated sulfite less than about 5 1 g./l. polyet y ene gyco 40 grams per iter, an

oleyl ether 2 I???) 5%.? 3 an alkylene oxide polymer selectedfrom the class, con- Y 7 sisting of (l) condensation products of alkylene 1 03mm 4000 2 1%. gig "g oxide with glycols, and (2) condensation products 7 J of an alkylene oxide with aliphatic com ounds se- .ii "i; lected from the class consisting, of aliphiitic mono- 1 ML Carbowax 6000 3 228. g g f hydric alcohols, aliphatic monobasic acids, aliphatic 5 .880 14.1 9 monoamrnes and monohydnc phenols, 1 cc. [1 muryl amine of Cap 5 23 8 said alkylene oxide containing from 2 to 4 carbon bownx 1500 4 .270 14.2 atoms and said alkylene oxide polymer having a g 328 1%; g molecular weight of at least 400, and said developer containing substantially only said p-dihydroxyben- In the table, dot quality is indicated by a scale of 1 iz g g agent as developmg agent for Sflver to 9 in which 1 is the poorest quality and 9 is the highest uality as determined by visual inspection. q It will be understood that the above examples are illus- Refekences Cited m the file of thls patent trative only, and that our invention is to be taken as lim- UNITED STATES PATENTS ited only by the scope of the appended claims. 2,886,437 Piper May 12, 1959 What we claim is: 2,902,367 Welliver et al Sept. 1, 1959 1. A photographic developer capable of prod cing 3,030,209 Henn et al. Apr. 17, 1962 high contrast images upon photographic development comprising a developing solution containing a p-dihydroxyhenzene developing agent, an amount of dissociated sulfite less than about 5 grams per liter, and

OTHER REFERENCES 6-36, Morgan and Lester, Publishers, New York, 1957. 

1. A PHOTOGRAPHIC DEVELOPER CAPABLE OF PRODUCING HIGH CONTRAST IMAGES UPON PHOTOGRAPHIC DEVELOPMENT COMPRISING A DEVELOPING SOLUTION CONTAINING A P-DIHYDROXYBENZENE DEVELOPING AGENT, AN AMOUNT OF DISSOCIATED SULFITE LESS THAN ABOUT 5 GRAMS PER LITER, AND AN ALKYLENE OXIDE POLYMER SELECTED FROM THE CLASS CONSISTING OF (1) CONDENSATION PRODUCTS OF ALKYLENE OXIDE WITH GLYCOLS, AND (2) CONDENSTATION PRODUCTS OF AN ALKYLENE OXIDE WITH ALIPHATIC COMPOUNDS SELECTED FROM THE CLASS CONSISTING OF ALIPHATIC MONOHYDRIC ALCOHOLS, ALIPHATIC MONOBASIC ACIDS, ALIPHATIC MONOAMINES AND MONOHYDRIC PHENOLS, SAID ALKYLENE OXIDE CONTAINING FROM 2 TO 4 CARBON ATOMS AND SAID ALKYLENE OXIDE POLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST 400, AND SAID DEVELOPER CONTAINING SUBSTANTIALLY ONLY SAID P-DIHYDROXYBENZENE DEVELOPING AGENT AS DEVELOPING AGENT FOR SILVER HALIDE. 